U.S. Pat. No. 3,646,177 to Thompson discloses a method for producing powdered metals and alloys that are free from oxidation by a process which involves atomizing molten metal with a fluid jet to form discrete particles of the molten metal. The jet is directed into a reservoir of an inert cryogenic liquid to solidify the particles and prevent oxidation during cooling.
U.S. Pat. No. 4,069,045 to Lundgren describes a process wherein a jet of molten metal is impinged against a rotating flat disc. Relatively thin, brittle, easily shattered, and essentially dentrite free metal flakes are obtained. These flakes are also described in U.S. Pat. No. 4,063,942 to Lundgren.
U.S. Pat. No. 4,221,587 to Ray relates to a method of making powder by impinging a jet of molten alloy at an acute angle against the inner surface of a rotating cylindrical chill body. As set forth in column 5, the impinging molten metal breaks into a stream of discrete droplets which bounce off the surface and move in the direction of the chill surface. Upon impact with the chill surface, the droplets are solidified at a rapid rate. As set forth in column 6, "the glassy metal powder particles ... have relatively sharp notched edges which enable the particles to interlock during compaction." As set forth in the first example, the particle size of the powder is such that 90% of the particles have a particle size range between about 25 and 300 microns.
U.S. Pat. No. 3,909,241 to Cheney et al relates to free flowing powders which are produced by feeding agglomerates through a high temperature plasma reactor to cause at least partial melting of the particles and collecting the particles in a cooling chamber containing a protective gaseous atmosphere where the particles are solidified.